The dual outbreaks of HIV infection and early (primary and secondary) syphilis among 15-30 year old African-American men who have sex with men (MSM) in North Carolina (NC) may be driven by men who are co-infected. Biologically, HIV and syphilis transmission are synergistic, in part because of the upregulation of HIV by syphilis infection. Epidemiologically, the velocity of transmission of HIV and other sexually transmitted diseases depends on the formation of sexual partnerships and the structure of sexual networks. Our preliminary data suggest that the sexual networks of African-American MSM are densely connected and co- infected men hold these networks together. Methamphetamine and Sildenafil (Viagra(R)) are important adjuvants in the spread of HIV and syphilis among urban white MSM. The association of crack and powder cocaine with heterosexual transmission of HIV and syphilis in the rural southeast is well established. Delineating sexual partnerships and transmission patterns within the networks of African-American MSM, and assessing the contribution of these drugs to formation of these networks will improve our understanding of the interrelationship of HIV infection, syphilis propagation, and the drug abuse epidemic. This study will extend our ongoing investigation of an epidemic of HIV infection that emerged in 2000 among predominately young, African-American MSM attending colleges and universities in and around Raleigh, NC to those diagnosed with syphilis. Routine activities of Disease Intervention Specialists (DIS), who interview persons newly diagnosed with syphilis and/or HIV, identify their infected sex partners and document risk behaviors including drug use. These data will permit construction of the sexual networks and drug use patterns of African-American men 15-30 years of age diagnosed with HIV or early syphilis during 2004-2008 in North Carolina. We will use these networks to pursue the following specific aims: AIM 1: Describe and compare the sexual networks of African-American men 15-30 years of age diagnosed with primary and secondary syphilis, HIV infection, and co-infection. AIM 2: Among African-American men 15-30 years of age, assess and compare individuals'position and centrality within sexual networks by diagnoses with primary and secondary syphilis, HIV infection, and co-infection, and evaluate the extent to which co-infected cases indirectly connect HIV cases to syphilis cases. AIM 3: Among African-American men 15-30 years of age diagnosed with primary and secondary syphilis, HIV infection, or co-infection, assess the extent of self-reported use of methamphetamines, erectile dysfunction medications, crack, and cocaine, and determine the relationship between drug use and membership in densely connected high risk sexual networks. PUBLIC HEALTH RELEVANCE: Young adult African-American men who have sex with men in North Carolina are experiencing rapidly expanding contemporaneous epidemics of HIV-infection, syphilis, and drug use. The sexual networks are complex and span across metropolitan, suburban, and rural areas. We will abstract data from public health records to characterize these networks, which will inform the development of new interventions and the improvement of existing ones to reduce morbidity and mortality among these people.